Abstract 3428: Plaque Fibrous Cap Macrophage Density and the Peripheral White Cell Count Predict the Presence of Thin-cap Fibroatheroma: an Intravascular Optical Coherence Tomography Study
Background: Histopathological data suggest most acute coronary events occur due to disruption of inflamed thin-cap fibroatheroma (TCFA). White blood cells (WBC) are important mediators of inflammation.
Aim: To evaluate the relationships between the peripheral WBC count, local plaque fibrous cap macrophage density (MΦ) and the presence of TCFA identified by optical coherence tomography (OCT).
Methods: OCT was performed in patients undergoing catheterization. Lipid was quantified as the number of quadrants on the cross-sectional image. TCFA were defined as lipid rich plaque (≥ 2 quadrants) with a fibrous cap thickness < 65μm. MΦ was calculated as the normalized standard deviation of the optical signal within the fibrous cap. WBC counts were obtained at baseline.
Results: 56 plaques from 43 patients were analyzed. There was significant correlation between plaque MΦ and WBC count (r = 0.48, p < 0.001). Plaques classified as TCFA had a higher MΦ [median (interquartile range)] than non-TCFA plaques [7.4 (1.8) vs 4.9 (2.0), p<0.001]. Similarly, patients with TCFA had a higher WBC count than those without TCFA [10.1 (1.9) vs 8.8 (3.1), p=0.007]. In a logistic regression model, MΦ and WBC count independently predicted the probability of TCFA. When receiver operator curves for WBC count, MΦ and the combined parameters were computed for prediction of TCFA, the area under the curves were 0.88, 0.91and 0.97 respectively (p< 0.001 for all, see figure⇓).
Conclusion: Fibrous cap MΦ, a marker of a plaques local inflammatory state, correlates with the peripheral WBC count, a marker of systemic inflammation. Both parameters independently and particularly in combination, predict the presence of TCFA.